There are a lot of armor skins in Halo 4 on the Xbox 360, but none of them may end up being as rare as the Fotus Armor.
The Fotus Armor wasn’t one of the many pre-order armor sets going around, it only comes with the Halo 4 Limited Edition console bundle, which is available for a cool $350.
They may release the skin as a separate DLC later, but for now this is the most expensive Halo 4 armor skin yet if that’s all you’re buying it for.
Alternatively, you could always buy a fotus armor code on ebay. At the time of writing this article, there are a lot for sale, but they still aren’t cheap.